Phlorotannins Research Articles

Fabrication and characterization of phlorotannins/poly (vinyl alcohol) hydrogel for wound healing application

Phlorotannins (PH) derived from brown algae have been shown to have biological effects. However, the application of PH in biomedical materials has not been investigated. Here, we investigated the effects of PH on normal human dermal fibroblast (NHDF) proliferation and fabricated a composite hydrogel consisting PH and poly (vinyl alcohol) (PVA) (PVA/PH) by a freezing-thawing method for wound healing applications. Cell proliferation was significantly higher in the PH-treated (0.01 and 0.02%) cells than in non-treated cells. Based on the mechanical properties, the PVA/PH hydrogel had a significantly increased swelling ratio and ultimate strain compared to the PVA hydrogel, but the ultimate tensile strength and tensile modulus were decreased. Additionally, cell attachment and proliferation on the composites were evaluated using NHDFs. The results showed that after 1 and 5 days, cell attachment and proliferation were significantly increased on the PVA/PH hydrogel compared with that on the PVA hydrogel. The findings from this study suggest that the PVA/PH hydrogel may be a candidate biomedical material for wound healing applications.

Influence of co-solvents on fucoxanthin and phlorotannin recovery from brown seaweed using supercritical CO2

Sunflower oil (SFO), soybean oil, canola oil, ethanol, and water were utilized as co-solvents to support supercritical carbon dioxide (SC-CO2) extraction of total carotenoid (TC), fucoxanthin (FX), and phlorotannin (PT) from brown seaweed (Saccharina japonica). A steepest ascent method with various temperatures [45–55°C], pressures [200–300bar], and co-solvent flow rates [0.50–2.00 (% of CO2, w/w)] was used to define the best operative co-solvents to enhance the extraction yields followed by response surface methodology (RSM) to optimize the extraction conditions. The best conditions for the yield of TC and FX were 50.62°C, 300bar, and 2.00% of SFO, while for PT it was 48.98°C, 300bar, and 2.00% of water, respectively. Overall extraction curves were determined for the optimized conditions, and experimental data were used to estimate the kinetic parameters. SFO as co-solvent showed higher fatty acid content, antioxidant activity, and oil stability than the control (SC-CO2 only).

Effect of a commercially-available algal phlorotannins extract on digestive enzymes and carbohydrate absorption in vivo

The ability of naturally occurring polyphenols and phlorotannins (PHTs) from some species of brown seaweeds to inhibit α-amylase and α-glucosidase enzymes in vitro has already been demonstrated. This study aimed at validating the efficacy of a new food ingredient extracted from Ascophyllum nodosum and Fucus vesiculosus PHTs at inhibiting digestive enzymes in vitro and slowing carbohydrate absorption in vivo. In vitro, the PHT extract completely inhibited in a dose-dependent fashion α-amylase and α-glucosidase with very low IC 50 values compared to other plant polyphenols. In animals, the PHT extract was able to reduce the normal increase in postprandial blood glucose seen 30 min after a meal by 90% (p < 0.05), and consecutively reduce peak insulin secretion by 40%. These results demonstrate the potency of this specific PHT extract to beneficially modulate carbohydrate digestion and assimilation, in a way that would be suitable for use in foods and dietary supplement formulations.

In vitro effects of phlorotannins from Ascophyllum nodosum (brown seaweed) on rumen bacterial populations and fermentation

AbstractBACKGROUND: Use of brown algae (seaweed) in ruminant diets is increasing, but the effects of its phlorotannins (PT) on rumen microbial ecology have not been determined. Mixed forage (50:25:25 ground barley silage–alfalfa hay–grass hay) was used as substrate in a batch culture ruminal incubation that included PT extracted from Ascophyllum nodosum, with and without polyethylene glycol. Principal ruminal bacteria were quantified using real‐time polymerase chain reaction.RESULTS: At 500 µg mL−1, PT reduced growth of Fibrobacter succinogenes by 78%, 83% and 65% at 6, 12 and 24 h (P &lt; 0.001), Ruminococcus albus at 24 h only (P &lt; 0.01) and did not affect R. flavefaciens. Non‐cellulolytic bacteria Selenomonas ruminantium, Ruminobacter amylophilus and Prevotella bryantii were increased (P &lt; 0.001) by PT at 12 and 24 h. Effects of PT on fermentation products (gas production, volatile fatty acid profiles and ammonia accumulation) were consistent with alterations in rumen microbial populations.CONCLUSION: The effects of PT on ruminal bacteria were species‐dependent, which suggests that diet may mediate PT effects on animal performance. The variation in sensitivity of ruminal bacteria to PT reflects previously reported effects of condensed tannins from terrestrial plants on microbial populations. Copyright © 2009 Crown in the right of Canada. Published by John Wiley &amp; Sons, Ltd

Sensitivity of Escherichia coli to Seaweed (Ascophyllum nodosum) Phlorotannins and Terrestrial Tannins

Pure culture experiments were conducted to assess the bacteriostatic and bactericidal effects of phlorotannins (PT) isolated from Ascophyllum nodosum (brown seaweed) on Escherichia coli O157:H7. In Exp. 1, one non-0157:H7 strain (25922) and three strains of E. coli O157:H7 (3081, EDL933 and E318N) were cultured in M9 medium with PT included at 0 (control), 25, 50 or 100 μg/ml (n = 3). Bacterial growth was monitored by OD 600 at 0, 4, 6, 12 and 24 h, and by dilution plating at 0, 4, 6 and 24 h. All strains were inhibited (p<0.001) by PT to varying degrees. At 50 or 100 μg/ml, PT prevented growth of all four strains. At 25 μg PT/ml, growth of 25922, 3081, E318N and EDL933 was inhibited for 6, 12 and 24 h, respectively, but 25922 and 3081 resumed growth by 12 and 24 h. Direct plating confirmed bactericidal effects of PT on all four strains at 100 mg/ml, and on EDL933 and E318N at 50 μg/ml. In Exp. 2, strains 25922 and 3081 were incubated with no tannins or with 50 μg/ml of PT, purified condensed tannins (CT) from Quebracho (Schinopsis balansaei), or purified tannic acid from Rhus semialata (Anacardiaceae) as hydrolysable tannins (HT). Strain 3081 was unaffected by HT or CT, but was completely inhibited (p<0.001) by PT at 4, 6 and 24 h. Strain 25922 was unaffected by HT, slightly inhibited by CT, and almost eradicated by PT at 4 and 6 h. Transmission electron microscopy revealed tannin-mediated alterations to bacterial cell walls. Phlorotannins from A. nodosum exhibit growth-inhibiting and bactericidal effects in vitro against the strains of E. coli O157:H7 investigated. Anti-E. coli efficacy of A. nodosum PT is superior to that of terrestrial tannins purified from Quebracho and from Rhus semialata.

Effects of phlorotannins from Ascophyllum nodosum (brown seaweed) on in vitro ruminal digestion of mixed forage or barley grain

The role of terrestrial tannins in livestock nutrition has been extensively investigated, but information on effects of tannins from marine sources on nutrient utilization is limited. This study investigated effect(s) of phlorotannins (PT) from the seaweed Ascophyllum nodosum on ruminal fermentation of mixed forage or barley grain. In 125-ml serum vials, buffered ruminal fluid inoculum (40 ml) was added to barley silage + alfalfa hay mixtures (500 mg/vial; Exp. 1) or ground barley grain (300 mg/vial; Exp. 2), together with crude seaweed extract in quantities to provide 0, 125, 250 or 500 μg PT/ml of medium, and polyethylene glycol (PEG; MW 3500) at 0 or 1 mg/ml. Gas production was measured at 0, 2, 4, 6, 8, 10, 12 and 24 h. Concentrations of volatile fatty acids (VFA) and ammonia, as well as in vitro digestibilities of neutral detergent fibre (aNDF; Exp. 1) and starch (Exp. 2) were determined at 0, 12, 24 and, Exp. 1 only, 48 h ( n = 3). Phlorotannins inhibited fermentation (P<0.05; linear), but PEG eliminated this response. Gas production and aNDF digestibility with mixed forage were greatly reduced by PT, with a minimal inhibitory concentration of 10 μg/ml as estimated by regression. With barley grain, regression analysis suggested that gas production and starch digestibility were inhibited at PT concentrations of 100 and 50 μg/ml, respectively. In Exp. 3, the forage mixture (500 mg) was incubated with PT at 0 or 500 μg/ml and PEG at 0 or 1 mg/ml, with 15N-labeled casein at 0.06 (w/v). Methane and total gas production, and concentrations of VFA and ammonia were measured at 0, 4, 8, 12 and 24 h ( n = 3). Net production of ammonia-N from casein ( i.e., 15N-NH 3) was lower (P<0.05) with PT than without, but was not altered by PT + PEG. Methane and total gas production were reduced (P<0.001) by PT throughout the 24-h incubation. With both diet types, in vitro ruminal fermentation and protein degradation were reduced by PT in a dose-dependent manner.